An independent panel of health experts that advises the federal government says theres not enough evidence to recommend for or against screening healthy adults for vitamin D levels. The US Preventive Services Task Force weighed more than a dozen studies before issuing its draft recommendation. As many as two-thirds of Americans are thought to be deficient in vitamin D. But its not clear, the task force stated, whether otherwise healthy people with low blood levels of vitamin D would benefit from supplementation if tested.
Although studies have shown people with low vitamin D are at greater risk of mortality and chronic disease, proving cause and effect has been tricky: It may be simply that low vitamin D is a marker for a less-healthy lifestyle, or that sicker people get less sun exposure, necessary for the body to make vitamin D. Theres also debate about exactly what level constitutes vitamin D deficiency.
For now, the task force advised, testing should be considered on a case by case basis. If youre concerned, consult your physician.